HYMENOPTERA 



33i 



The legs of the Hymenoptera present characters that are much used 

 in the classification of these insects. Among the more striking of these 



Fig. 574- — Head 

 of a honey-bee: a, 

 antenna; c, clypeus; 

 u, labrum; m, man- 

 dible; mx, maxilla; 

 p, labial palpus; /, 

 labium. 



Fig. 575. — Leg of an ant, and strigilis enlarged. 

 (From A. B. Comstock, Handbook of Nature Study.) 



are the following; the trochanter may consist of two segments (Fig. 

 64, B) or of only one; the metatarsus of the hind legs is greatly en- 

 larged in bees (Fig. 64, C); and in several families the fore legs are 

 fitted with an organ which is used in cleaning the antennas, the antenna 

 cleaner or strigilis. This consists of a curved, comb-like, movable spur 

 on the distal end of the fore tibia (Fig. 575) and opposite this, on the 

 base of the metatarsus, a concavity fringed with hairs. In cleaning an 

 antenna it is drawn through the space between these two parts of the 

 strigilis. 



In the Hymenoptera the metamorphosis is complete. The larvae of 

 the first suborder are caterpillar-like in form and are furnished with 

 thoracic legs and usually with abdominal prolegs; but in some, mostly 

 borers or internal feeders, the prolegs are wanting. In all the forms of 

 the third suborder the larvae are maggot-like in form and have no legs. 

 The pupae are of the exarate type, that is, the legs and wings are free, as 

 in the Coleoptera. With many species the larva, before changing to 

 a pupa, spins a cocoon about its body. With some this cocoon is com- 

 posed of comparatively loose silk, and resembles somewhat the cocoon 

 of a moth. In others the cocoon is of a dense parchment-like texture, 

 and in still others it resembles a very delicate foil. 



Parthenogenesis. — The production of young by females that have not 

 mated is known to occur in members of several families of this order. 

 In some species the young thus produced are all males; in others they 

 are all females; and in still others both males and females are developed 

 from unfertilized eggs. 



Polyembryony. — In several genera of minute parasitic Hymenoptera 

 the number of young produced is not dependent upon the number of 

 eggs laid, for with these insects many embryos are developed from a 

 single egg. This type of development is termed polyembryony. 



THE CLASSIFICATION OF THE HYMENOPTERA 



The sequence of the families and arrangement of the groups adopted 

 in this chapter are after Messrs. J. C. Bradley, S. A. Rohwer, and J. 



